Results are presented on a measurement of the tt̅ pair production cross section in pp̅ collisions at √s = 1.8 TeV from nine independent decay channels. The data were collected by the DØ experiment during the 1992–1996 run of the Fermilab Tevatron Collider. A total of 80 candidate events is observed with an expected background of 38.8±3.3 events. For a top quark mass of 172.1 GeV/c2, the measured cross section is 5.69 ±1.21(stat) ±1.04(syst) pb